A low density, refractory stopper rod sleeve has a substantially imperforate surface and a core containing a plurality of randomly spaced, internal and discontinuous small voids. The density of the sleeve is less than 2.0 gr./cc and the preferred density range is 1.60 to 1.85 gr./cc. The sleeve is made up of six parts by volume refractory clay mix to four parts of a combustible waste material such as wet sawdust which does not exceed a screen size of 10 mesh. The sleeves are made by the stiff mud process which includes extruding the mix into solid, cylindrical blanks and forming the blanks in a die in which the final sleeve is slidably disengaged from the die. After drying the sleeve is processed through a normal firing cycle until it reaches approximately 1500.degree.F at which time it is held for a prolonged period of time to drive off the carbonaceous material associated with the waste combustible in the mix.